Filter cake cleanup and gravel pack methods for oil based or water based drilling fluids

摘要

A method is disclosed of gravel packing a wellbore which has at least one aperture therein that provides a fluid flow path between the wellbore and an adjacent subterranean formation. At least a part of the formation adjacent to the open hole has a filter cake coated thereon that comprises a water and oil emulsion. The method of gravel packing comprises injecting into the wellbore a gravel pack composition that comprises gravel and a carrier fluid. The carrier fluid comprises an aqueous liquid having a pH that is outside the range at which the filter cake emulsion is stable. The aqueous liquid is present in an amount effective to invert the water in oil emulsion in the filter cake when the carrier fluid comes into contact with the filter cake. As a result, gravel is deposited at or adjacent to the aperture in the wellbore and some of the filter cake is removed. The remainder of the filter cake and the carrier fluid can be broken simultaneously by contact with a breaker fluid that contains at least one of a surfactant and a mutual solvent.